assertRejects | /assert/mod.ts | std@0.223.0

function assertRejects

import { assertRejects } from "https://dotland.deno.dev/std@0.223.0/assert/mod.ts";

assertRejects(fn: () => PromiseLike<unknown>, msg?: string): Promise<unknown>

Executes a function which returns a promise, expecting it to reject.

assertRejects<E extends Error = Error>(

fn: () => PromiseLike<unknown>,

ErrorClass: new (...args: any[]) => E,

msgIncludes?: string,

msg?: string,

): Promise<E>

Executes a function which returns a promise, expecting it to reject. If it does not, then it throws. An error class and a string that should be included in the error message can also be asserted.

Executes a function which returns a promise, expecting it to reject.

To assert that a synchronous function throws, use assertThrows.

Examples

Example 1

import { assertRejects } from "https://deno.land/std@0.223.0/assert/assert_rejects.ts";

await assertRejects(async () => Promise.reject(new Error())); // Doesn't throw
await assertRejects(async () => console.log("Hello world")); // Throws

Parameters

fn: () => PromiseLike<unknown>

optional

msg: string

Returns

Promise<unknown>

Executes a function which returns a promise, expecting it to reject. If it does not, then it throws. An error class and a string that should be included in the error message can also be asserted.

To assert that a synchronous function throws, use assertThrows.

Examples

Example 1

import { assertRejects } from "https://deno.land/std@0.223.0/assert/assert_rejects.ts";

await assertRejects(async () => Promise.reject(new Error()), Error); // Doesn't throw
await assertRejects(async () => Promise.reject(new Error()), SyntaxError); // Throws

Type Parameters

optional

E extends Error = Error

Parameters

fn: () => PromiseLike<unknown>

ErrorClass: new (...args: any[]) => E

optional

msgIncludes: string

optional

msg: string

Returns

Promise<E>